All good suggestions… here's some more…
Use a good quality
latex paint… so much easier to clean up afterwards since it's a water based paint.
Don't use the paint directly from the can… by that I mean, buy one of those paint cups… has a handle on it and hold perhaps a pint or so. This allows you to stir the paint in the can every time you refill the 'cup' and the paint in the can doesn't begin to dry out from being uncovered. Like this:
http://www.homedepot.com/p/Earth-Plastic-Plastic-Paint-Trim-Cup-PTC710-40HE/202019634 .
If, you choose to use the paint directly from the can, use a common nail and punch 8 or 10 holes in the valley where the can lid fits into to seal it. This will allow the paint that accumulates there when filling your brush (ala jourdain2's method) to drain back into the can.
Go to your store of choice and by a largish bottle of the cheapest washing fabric softener you can find. You know the kind (I'm in the U.S.) usually pink, smells great and one pours it into a dispenser on the washing machine when doing the laundry. Well… this stuff is the world's best for cleaning brushes and rollers when stopping for the day. Fill a good size pail (one of the cheap, plastic 5 gallon ones that you find at your DIY store) with warm water and pour a large amount (really doesn't matter how much… even the full bottle) of the fabric softener into the pail and stir. Then, simply put your paint rollers and brushes in the pail and swish around thoroughly… rinse in clear water
et voila they come out clean and ready to use next time. Rather than trying to dry the brushes, simply hand them up (they have a hole in the handle for this) and let them drip dry.
As to brushes… buy the best quality you can find in about 2 1/2 or 3 inch width with the end tapered. This helps when 'cutting in' borders, etc. When the brush is thoroughly dry as above, wrap it in the Saran type wrap… you know… the sticky clear plastic wrap in the kitchen. This will help it maintain it's original shape when storing.
Rollers… but an extension handle for the roller holder. That way you can stand away from the application… less tiring and gives a better perspective on the finished product. The extension handle should slide in and out of itself with a screwing device to hold the length you want.
Finally, but a package of roller tray fillers… these are inexpensive plastic devices made to fit inside of your roller tray. When you're through, simply discard them.
Good luck!